U.S. patent application number 11/608026 was filed with the patent office on 2008-01-03 for flame retardant rubber-modified styrene resin composition.
This patent application is currently assigned to LG CHEM, LTD.. Invention is credited to Jong-kuk CHOI, Yong-yeon HWANG, Dae-san JUNG, Sung-ho LEE, Boo-ho SEO.
Application Number | 20080004378 11/608026 |
Document ID | / |
Family ID | 38845726 |
Filed Date | 2008-01-03 |
United States Patent
Application |
20080004378 |
Kind Code |
A1 |
CHOI; Jong-kuk ; et
al. |
January 3, 2008 |
FLAME RETARDANT RUBBER-MODIFIED STYRENE RESIN COMPOSITION
Abstract
The present invention relates to a flame retardant
rubber-modified styrene resin composition having excellent flame
resistance for dripping without containing halogens and phenylene
ether, which comprises A) 100 weight part of a rubber-modified
polystyrene; B) 1.about.10 weight part of a phosphoric ester
compound; and C) 0.1.about.10 weight part of an aliphatic amide
compound. The flame retardant rubber-modified styrene resin
composition of the present invention has flame resistance at the
level of UL-94 V-2 and excellent impact resistance, heat resistance
and fluidity.
Inventors: |
CHOI; Jong-kuk; (Gwangju-si,
KR) ; JUNG; Dae-san; (Daejeon, KR) ; LEE;
Sung-ho; (Daejeon, KR) ; HWANG; Yong-yeon;
(Daejeon, KR) ; SEO; Boo-ho; (Daejeon,
KR) |
Correspondence
Address: |
CANTOR COLBURN, LLP
55 GRIFFIN ROAD SOUTH
BLOOMFIELD
CT
06002
US
|
Assignee: |
LG CHEM, LTD.
Seoul
KR
|
Family ID: |
38845726 |
Appl. No.: |
11/608026 |
Filed: |
December 7, 2006 |
Current U.S.
Class: |
524/115 |
Current CPC
Class: |
C08K 5/523 20130101;
C08K 5/523 20130101; C08K 5/20 20130101; C08K 5/20 20130101; C08L
51/04 20130101; C08L 51/04 20130101 |
Class at
Publication: |
524/115 |
International
Class: |
C08K 5/49 20060101
C08K005/49 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 29, 2006 |
KR |
10-2006-0059559 |
Claims
1. A flame retardant rubber-modified styrene resin composition that
characteristically contains: A) 100 weight part of a
rubber-modified styrene copolymer; B) 1.about.10 weight part of a
non-halogen phosphoric ester compound as a flame-retardant; and C)
0.1.about.10 weight part of an aliphatic amide compound as a
dropping enhancer.
2. The flame retardant rubber-modified styrene resin composition
according to claim 1, wherein the rubber-modified styrene copolymer
of A) has such a structure that rubber polymer particles are
dispersed on a matrix composed of a copolymer of a vinyl aromatic
polymer and compound copolymerizible with a vinyl aromatic
compound.
3. The flame retardant rubber-modified styrene resin composition
according to claim 2, wherein the rubber polymer is one or more
compounds selected from a group consisting of acrylate or
methacrylate containing rubber polymers; polybutadiene;
styrene-butadiene-styrene copolymer; styrene-butadiene copolymer;
polyisoprene; butadiene-isoprene copolymer; and natural rubber.
4. The flame retardant rubber-modified styrene resin composition
according to claim 1, wherein the non-halogen phosphoric ester
compound of B) is one or more compounds selected from a group
consisting of trialkylphosphate, triarylphosphate,
trialkyl-arylphosphate and aromatic diphosphate represented by
formula 1. ##STR00003## Wherein, Ar.sub.1.about.Ar.sub.4 are phenyl
or aryl with the substitution of 1.about.3 C1.about.C4 alkyl, R is
phenyl or bisphenol A, and n is the degree of polymerization.
5. The flame retardant rubber-modified styrene resin composition
according to claim 4, wherein the trialkylphosphate is selected
from a group consisting of trimethylphosphate, triethylphosphate,
tributylphosphate and trioctylphosphate.
6. The flame retardant rubber-modified styrene resin composition
according to claim 4, wherein the triarylphosphate is selected from
a group consisting of triphenylphosphate, tricresylphosphate,
trixylenylphosphate and cresyldiphenylphosphate.
7. The flame retardant rubber-modified styrene resin composition
according to claim 4, wherein the trialkyl-arylphosphate is
octyldiphenylphosphate.
8. The flame retardant rubber-modified styrene resin composition
according to claim 1, wherein the aliphatic amide compound of C) is
one or more compounds selected from a group consisting of
stearamide, oleamide, erucamide, ethylene bis stearamide and
ethylene bis oleamide, represented by formulas 2 or 3. ##STR00004##
Wherein, R is C.sub.12.about.C.sub.22 alkyl.
9. The flame retardant rubber-modified styrene resin composition
according to claim 1, wherein the composition additionally includes
antioxidants, heat stabilizers, photo stabilizers, lubricants,
anti-dripping agents, inorganic fillers, or pigments.
Description
[0001] This application claims the benefit of the filing date of
Korean patent Application Nos. 10-2006-0059559 filed on Jun. 29,
2006 in the Korean Intellectual Property Office, the disclosure of
which is incorporated herein in its entirety by reference.
TECHNICAL FIELD
[0002] The present invention relates to a flame retardant
rubber-modified styrene resin composition, and more precisely a
flame retardant non-halogen rubber-modified styrene resin
composition with improved flame resistance for dripping, impact
resistance, heat resistance and fluidity without using a halogen
flame retardant and polyphenylene ether.
BACKGROUND ART
[0003] Rubber-modified styrene resin, a representative impact
resistant polystyrene resin, is characterized by excellent
plasticity, strength, and electrical properties. Owing to these
characteristics, this resin has been widely applied to various
industrial fields including office automation devices such as
word-processors, personal computers, printers, copiers, etc; home
electronic appliances such as TVs, VCRs, audio systems, etc;
electronic parts; and auto parts.
[0004] Even with these excellent plasticity and mechanical
properties, the flammable rubber-modified styrene resin has a
safety problem. Therefore, efforts have been continuously made to
develop a flame retardant rubber-modified styrene resin. The flame
resistance has been controlled by UL and the method in which
halogen flame-retardants are mixed with styrene resin together with
a flame retardant auxiliary has been the most commonly accepted.
The halogen flame-retardant is selected from a group consisting of
polybromodiphenylether, tetrabromobisphenol A, Br-substituted epoxy
compound and chlorinated polyethylene. The flame retardant
auxiliary is an antimony compound such as antimony trioxide and
antimony pentoxide.
[0005] The method of generating flame-resistance by mixing a
halogen flame retardant with the antimony flame retardant auxiliary
has been successful at endowing excellent flame-resistance without
damaging the mechanical properties, but there are chances of
damaging the mold from hydrogen halide during the processing, and
producing dioxin, a strong carcinogen, from the waste incineration,
causing environmental and biological problems. Recently, actions
have been taken to restrict such halogen flame retardants and thus
there is a need to develop a flame retardant resin excluding
halogen elements.
[0006] To endow flame resistance to a rubber-modified styrene resin
that does not include halogen elements, a rubber-modified styrene
resin has been blended with polyphenylene ether, which is expected
to improve flame resistance and heat resistance.
[0007] U.S. Pat. No. 3,639,506 and No. 3,883,613 describe that it
is effective to add an aromatic phosphoric ester such as
triphenylphosphate and trimesitylphosphate as a flame retardant to
the blend of rubber-modified styrene resin and polyphenylene ether
resin. U.S. Pat. No. 6,124,385 describes that flame resistance is
improved by adding a free radical generator and triphenylphosphate
or triphenylphosphineoxide alone or together to the mixture of
rubber-modified styrene resin and polyphenylene ether resin.
[0008] During the processing of the polyphenylene ether and
rubber-modified styrene blend into a flame-retardant resin, the
processing temperature is high because of the heat-resistant
polyphenylene ether and the screw has to be separately designed to
handle the huge shear force. At this time, if the processing
temperature is 250.degree. C. or higher, the low molecular aromatic
phosphoric ester will evaporate, suggesting that the final content
of the compound in the final resin is much less than at the early
stage, so flame resistance and the physical properties will be
altered. An increase of polyphenylene ether content is a
disadvantage for preparing a flame retardant resin for dripping
because the over-dose of polyphenylene ether inhibits the dripping
of the flame retardant resin.
[0009] In the course of studies on the development of a flame
retardant rubber-modified styrene resin with excellent flame
resistance for dripping and without polyphenylene ether to overcome
the above problems, the present inventors completed this invention
by confirming that the flame resistance for dripping of a resin is
greatly improved when a phosphoric ester compound is used as a
flame retardant and an aliphatic amide compound is used as a
dripping enhancer without damaging heat resistance and
fluidity.
DISCLOSURE OF THE INVENTION
[0010] It is an object of the present invention to provide a
rubber-modified styrene resin having excellent flame resistance for
dripping without using polyphenylene ether. It is another object of
the present invention to provide a flame-retardant rubber-styrene
resin having excellent physical properties including heat
resistance, impact resistance and fluidity.
[0011] The above object and other objects of the present invention
can be achieved by the following embodiments of the present
invention.
[0012] To achieve the objects of the present invention, an
embodiment of the present invention provides a flame-retardant
rubber-modified styrene resin composition that characteristically
contains:
[0013] A) 100 weight part of a rubber-modified styrene
copolymer;
[0014] B) 1.about.10 weight part of a non-halogen phosphoric ester
compound as a flame-retardant; and
[0015] C) 0.1.about.10 weight part of an aliphatic amide compound
as a dripping enhancer.
[0016] The present invention is described in detail
hereinafter.
[0017] A) Rubber-Modified Styrene Copolymer
[0018] The rubber-modified styrene copolymer of the present
invention is a major component of the resin composition, which
plays a role in supporting the molded goods. The rubber-modified
styrene resin has a structure such that rubber polymer particles
are dispersed on a matrix composed of a copolymer of a vinyl
aromatic polymer and any compound that is able to be copolymerized
with the vinyl aromatic polymer. Polymerization is performed by
either bulk polymerization, suspension polymerization or emulsion
polymerization, and bulk polymerization is more preferred. When
bulk polymerization is performed, a rubber polymer is dissolved in
a vinyl aromatic monomer followed by stirring and then a
polymerization initiator is added thereto.
[0019] The vinyl aromatic monomer used to produce the
rubber-modified styrene copolymer is largely a styrene compound. In
addition to the styrene compound, nucleus alkyl substituted styrene
such as p-methylstyrene, 2,4-dimethylstyrene or
.alpha.-ethylstyrene; methylstyrene or .alpha.-alkyl substituted
styrene such as .alpha.-methyl-p-methylstyrene can be used as the
vinyl aromatic compound of the present invention. The styrene
compound can be used alone or in a mixture of at least two
compounds.
[0020] The rubber polymer used for the rubber-modified styrene
copolymer is selected from a group consisting of acrylate or
methacrylate containing rubber polymers; polybutadiene or
styrene-butadiene-styrene copolymer; styrene-butadiene copolymer;
polyisoprene or butadiene-isoprene copolymer; and natural rubber.
Polybutadiene or styrene-butadiene copolymer is preferred, and
polybutadiene is more preferred.
[0021] B) Phosphoric Ester Compound
[0022] The phosphoric ester compound is used in the present
invention to improve the flame-resistance of a rubber-modified
styrene copolymer, and is selected from a group consisting of
trialkylphosphate without halogen substitution such as
trimethylphosphate, triethylphosphate, tributylphosphate and
trioctylphosphate; a triarylphosphate such as triphenylphosphate,
tricresylphosphate, trixylenylphosphate and
cresyldiphenylphosphate; a trialkyl-arylphosphate such as
octyldiphenylphosphate; and an aromatic diphosphate represented by
the following formula 1. Among these compounds, triarylphosphate is
preferred and triphenylphosphate, tri(4-methylphenyl)phosphate or
tri(2,6-dimethylphenyl)phosphate is more preferred.
##STR00001##
[0023] Wherein, Ar.sub.1.about.Ar.sub.4 are phenyl or aryl with the
substitution of 1.about.3 C1.about.C4 alkyl, R is phenyl or
bisphenol A, and n is the degree of polymerization.
[0024] The preferable content of the phosphoric ester compound in
100 weight part of the rubber-modified styrene copolymer is
1.about.10 weight part. If the content of the flame retardant is
less than 1 weight part, the flame retardant effect will be
reduced. Also, if the content of the flame retardant is more than
10 weight part, heat resistance will be reduced seriously.
[0025] C) Aliphatic Amide Compound
[0026] The aliphatic amide compound used in the present invention,
which is represented by formula 2 or 3, plays a role in improving
the dripping of a flame retardant rubber-modified styrene resin,
which is exemplified by stearamide, oleamide, erucamide, ethylene
bis stearamide, ethylene bis oleamide, etc. Particularly, ethylene
bis stearamide is preferably used.
##STR00002##
[0027] Wherein, R is C.sub.12.about.C.sub.22 alkyl.
[0028] The preferable content of the aliphatic amide compound in
100 weight part of rubber-modified styrene copolymer is
0.1.about.10 weight part. If the content of such a dripping
enhancer is less than 0.1 weight part, dripping property will not
be enhanced. In the meantime, if the content is more than 10 weight
part, heat resistance and thermostability will be reduced.
[0029] The flame retardant rubber-modified styrene resin
composition of the present invention can additionally include
antioxidants, heat stabilizers, photo stabilizers, lubricants,
anti-dripping agents, inorganic fillers, pigments, etc.
BEST MODE FOR CARRYING OUT THE INVENTION
[0030] Practical and presently preferred embodiments of the present
invention are illustrated as shown in the following examples.
[0031] However, it will be appreciated that those skilled in the
art, on consideration of this disclosure, may make modifications
and improvements within the spirit and scope of the present
invention.
EXAMPLES
Example 1
[0032] Preparation of Rubber-Modified Styrene Resin
[0033] A monomer mixture composed of 8 weight part of butadiene
rubber, 77 weight part of styrene and 15 weight part of
ethylbenzene was prepared, to which 0.02 weight part of
1,1-bis(t-butyl peroxy)-3,3,5-trimethyl cyclohexane was added as a
polymerization initiator. The mixture was put in a continuous
polymerizing apparatus wherein 4 stirred tank reactors were
serially connected, followed by continuous graft copolymerization.
The temperature at the entrance of the polymerizing apparatus was
125.degree. C., and the temperature at the exit was 140.degree. C.
The final copolymerization solution was transferred into the
devolatilizing tank, where non-reacted monomers and solvent were
eliminated at 230.degree. C. under 20 torr, followed by pelleting
to give a rubber-modified styrene resin (HIPS) containing 8 weight
% of rubber.
[0034] Preparation of Flame Retardant Rubber-Modified Styrene
Resin
[0035] To 100 weight part of the rubber-modified styrene resin
prepared above were added 3 weight part of triphenylphosphate
(Daihachi, Japan), a flame retardant, 3 weight part of ethylene bis
stearamide as a dripping enhancer (Sunkoo Chem., Korea), and 0.3
weight part of an antioxidant (Ciba Specialty Chemicals iganox
1076). The above compounds were mixed well in a Henschel mixer,
followed by extrusion at 210.degree. C. using a twin screw extruder
to prepare a pellet. The final sample was prepared by
injecting.
Example 2
[0036] A flame retardant rubber-modified styrene resin was prepared
in the same manner as described in Example 1 except that 0.5 weight
part of stearamide (Akzo) was used as a dripping enhancer.
Example 3
[0037] A flame retardant rubber-modified styrene resin was prepared
in the same manner as described in Example 1 except that 7 weight
part of resorcinol tetraxylyloxy diphosphate PX-200 (Daihachi,
Japan) was used as a flame retardant and 5 weight part of ethylene
bis stearamide (Sunkoo chem., Korea) was used as a dripping
enhancer.
Comparative Example 1
[0038] A flame retardant rubber-modified styrene resin was prepared
in the same manner as described in Example 1 except that 80 weight
part of the rubber-modified styrene resin and 20 weight part of
polyethylene ether were used and extrusion was performed at
250.degree. C. without using a dripping enhancer.
Comparative Example 2
[0039] A flame retardant rubber-modified styrene resin was prepared
in the same manner as described in Example 1 except that 3 weight
part of triphenylphosphate was used and a dripping enhancer was not
used.
Comparative Example 3
[0040] A flame retardant rubber-modified styrene resin was prepared
in the same manner as described in Example 1 except that 15 weight
part of triphenylphosphate was used and a dripping enhancer was not
used.
Comparative Example 4
[0041] A flame retardant rubber-modified styrene resin was prepared
in the same manner as described in Example 1 except that 12 weight
part of ethylene bis stearamide was used.
Comparative Example 5
[0042] A flame retardant rubber-modified styrene resin was prepared
in the same manner as described in Example 1 except that 3 weight
part of zinc stearate was used as a dripping enhancer.
Comparative Example 6
[0043] A flame retardant rubber-modified styrene resin was prepared
in the same manner as described in Example 1 except that 3 weight
part of polyethylene wax was used as a dripping enhancer.
Comparative Example 7
[0044] A flame retardant rubber-modified styrene resin was prepared
in the same manner as described in Example 1 except that 3 weight
part of fatty acid ester compound was used as a dripping
enhancer.
Experimental Example
[0045] The flame retardant rubber-modified styrene resins prepared
in Examples 1.about.3 and Comparative Examples 1.about.7 were
tested for impact resistance and weather resistance as follows.
[0046] a) Flammability--tested with 1/8'' bar sample according to
the UL94 VB flammability test method
[0047] b) Impact resistance--tested with 1/8'' notch sample
according to ASTM D256 by measuring izod impact strength
(kgcm/cm).
[0048] c) Heat resistance--tested with 1/4'' sample according to
ASTM D648 by measuring heat distortion temperature (HDT).
[0049] d) Fluidity--tested under the conditions of 200.degree. C.
and 5 kg according to ASTM D1238.
[0050] The flame resistance and physical properties measured by the
above methods are shown in Table 1.
TABLE-US-00001 TABLE 1 Example Comparative Example 1 2 3 1 2 3 4 5
6 7 HIPS 100 100 100 80 100 100 100 100 100 100 PPE -- -- -- 20 --
-- -- -- -- -- Phosphoric ester TPP 3 3 -- 3 3 15 3 3 3 3 compound
PX-200 -- -- 7 -- -- -- -- -- -- -- Aliphatic amide Stearamide --
0.5 -- -- -- -- -- -- -- -- compound EBS 3 -- 5 -- -- -- 12 -- --
-- Zinc stearate -- -- -- -- -- -- -- 3 -- -- PE wax -- -- -- -- --
-- -- -- 3 -- Fatty acid ester -- -- -- -- -- -- -- -- -- 3 Heat
stabilizer 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Izod impact
strength (kgfcm/cm, 1/8'') 14 13 12 16 15 13 12 15 15 14 Heat
distortion temperature (.degree. C.) 76 77 75 81 77 61 63 77 76 77
Melt index (g/min) 15 13 18 5 14 45 34 13 12 16 Flammability
(1/8'') V-2 V-2 V-2 V-2 N/R V-2 V-2 N/R N/R N/R Total burning time
(sec) 28 34 26 47 -- 23 35 -- -- -- * N/R: No Rating * EBS:
ethylene bis stearamide
[0051] As shown in Table 1, the flame retardant rubber styrene
resins of Examples 1.about.3, which were prepared with the addition
of a phosphoric ester compound as a flame retardant and aliphatic
amide compound a dripping regulator without polyphenylene ether,
were confirmed to have stable flame resistance according to UL-94
V-2 and maintained an excellent balance among the mechanical
properties including impact resistance, heat resistance and
fluidity.
[0052] Particularly, the flame retardant rubber-modified styrene
resin of Comparative Example 1 had flame resistance for dripping
but the total burning time was longer with reduced fluidity. In the
meantime, the resins of Comparative Examples 2, 5, 6 and 7 wherein
a dripping regulator was not included and a non-aliphatic amide
lubricant was included had excellent mechanical properties but
unsatisfactory flame resistance. As shown in Comparative Examples 3
and 4, excellent flame resistance for dripping can be achieved by
the over-use of a phosphoric ester compound and aliphatic amide
compound, which has the disadvantage of a serious reduction in heat
resistance.
INDUSTRIAL APPLICABILITY
[0053] As explained hereinbefore, the flame retardant
rubber-modified styrene resin composition of the present invention
can maintain flame resistance according to UL-94 V-2 without any
halogen compound or polyphenylene ether and has excellent impact
resistance, heat resistance and fluidity. The flame retardant
rubber-modified styrene resin composition of the present invention
can be applied to various fields particularly to OA devices and TV
housings, owing to the slight chance of outward inferiority under
various molding conditions.
[0054] Those skilled in the art will appreciate that the
conceptions and specific embodiments disclosed in the foregoing
description may be readily utilized as a basis for modifying or
designing other embodiments for carrying out the same purposes of
the present invention. Those skilled in the art will also
appreciate that such equivalent embodiments do not depart from the
spirit and scope of the invention as set forth in the appended
claims.
* * * * *